The field of the present invention relates to optical systems for data reading and particularly to a scanning system having improved resistance to shock and vibration.
Typically a data reading device such as a bar code scanner illuminates a bar code and senses light reflected from the code to detect the bars and spaces of the code symbols and thereby derive the encoded data. In a common system, an optical beam of light, such as a laser beam produced by a laser diode is scanned over a scan angle so as to scan the laser spot across the item being read. A variety of mechanical scanning mechanisms are known as described in for example U.S. Pat. Nos. 5,475,206 and 5,629,510 or U.S. application Ser. No. 08/934,487, each of these disclosures hereby incorporated by reference, such scanning mechanisms comprising a rotating polygon mirror, dithering or oscillating mirror, scanning light source or laser diode, rotating/oscillating prisms, holographic elements and others devices. Essentially all these scanners include a supporting structure which allows for movement of the mechanical scanning mechanism.
Current mechanical scanning mechanisms are relatively sensitive to shock. Handheld scanners are particularly subjected to shock and have been equipped with shock protection such as by containing the scanning mechanism within a scan module and mounting the scan module within a housing via shock mounts as described in U.S. Pat. No. 5,475,206, incorporated by reference. Nonetheless because of this sensitivity to shock and the use of these devices in hand-held applications, these scanners and scan engines are often damaged before they would have worn out for other reasons.